The proposed research will evaluate the effects of prenatal and postnatal disturbance of immune responses in infant and aged primates. Three areas of study are proposed: (1) the effect of prenatal stress on immune responses in infant squirrel monkeys and rhesus monkeys. (2) the long-term effects of abnormal, early rearing on immune responses in middle-aged monkeys, and (3) the effect of social companionship and disturbance on immune responses in aged monkeys. The squirrel monkey studies will focus primarily on macrophage responses, including phagocytic and tumoricidal activity, and the production of interleukin-1Beta and Alpha interferon. Infants will be derived from undisturbed. socially stressed, and dexamethasone-treated pregnancies. Changes in immune responses during weaning from the mother will be evaluated in infants from the 3 types of pregnancies to determine whether prenatal events establish a vulnerability to subsequent challenge. Comparable studies on rhesus monkey infants will focus more specifically on the relationship between immunological, behavioral, and neurological development. A second series of studies will focus on the possible effects of early rearing environments on immune responses in adult monkeys. Based on prior studies showing that the length of time that an infant spent with its mother influenced later immune responses, we will utilize a standardized panel to assess the immune status of differentially-reared, middle-aged monkeys. The third area of research will evaluate the effects of social companionship and disturbance on T cell immunity in aged female monkeys. The measures will include lymphocyte proliferation, natural killer cell activity cell markers, and antibody response to vaccination. Previous studies have shown that the rhesus monkey is a suitable model for investigating the process of immune senescence, and the proposed experiments will assess whether immune responses in the aged monkey are significantly affected by social companionship and loss. The goal of the research program is to evaluate the relationship between psychological factors and immunity within a life span perspective.